The subject matter disclosed herein relates to a computed tomography (CT) detector apparatus including a heat pipe.
Typically, in CT systems, an x-ray source emits an x-ray beam toward a subject or object, such as a patient or a piece of luggage, positioned on a support. The x-ray beam, after being attenuated by the object, impinges upon a detector assembly. The intensity of the attenuated x-ray beam received at the detector assembly is typically dependent upon the attenuation of the x-ray beam by the object.
In known third generation CT systems, the x-ray source and the detector assembly are rotated on a rotatable gantry portion around the object to be imaged so that a gantry angle at which the x-ray beam intersects the object constantly changes. The detector assembly typically includes a plurality of detector modules. Each detector module is typically divided into a plurality of detector elements. Data representing the intensity of the received x-ray beam at each of the detector elements are collected across a range of gantry angles. The data are ultimately processed to form an image.
The electronic components produce heat that may cause a degradation in image quality through multiple mechanisms. For example, the gain of a photodiode layer within the detector module is highly temperature dependent and operating the photodiode layer at too high of a temperature may lead to image artifacts such as spots or rings. Also, the amount of pixel-to-pixel leakage between photodiodes increases with temperature. A high level of pixel-to-pixel leakage negatively impacts the signal to noise ratio and may result in reduced image quality. Also, an increase in the temperature of the detector module may result in problems with the mechanical alignment of the detector assembly and a collimator. Third generation CT imaging systems rely on an accurately aligned collimator to effectively block scattered x-ray. However, the mechanical alignment of the detector assembly and the collimator may change as the temperature increases outside of an optimal operating range. If the collimator is not properly aligned with the detector assembly, the result may be additional image artifacts.
The problem is that excessive heat within the detector assembly may lead to image artifacts from multiple sources, resulting in images of diminished quality.